06252018Mon
Last updateFri, 22 Jun 2018 2pm

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VMA Technical Event: Engineering Valves in the Extreme

While much the 2017 VMA Technical Seminar, held March 2-3 in Nashville, focused on numbers, statistics and specifications, attendees were reminded in a highly charged, emotional presentation by safety awareness speaker Brad Livingston just why it is important to be so vigilant when engineering valves in the extreme.

In “Just a Second Ago” Livingston recounted the events of 1991 when he nearly lost his life because of decisions he and a co-worker made to shave a few moments off a welding job on a natural gas pipeline. According to Livingston, the two explosions—which were 100% preventable—happened because standard safety procedures were ignored. He blamed himself for not speaking up and insisting they be followed, and his plea to those gathering for this event was: “Consider, what is it worth?”

Natural Gas Outlook Keynote Address

Angelina LaRose, director of the Office of Integrated and International Energy Analysis at the U.S. Energy Information Administration (EIA) offered that organization’s predictions for natural gas production and prices for the duration of 2017. While all forecasts are tempered by unexpected political and environmental developments worldwide, LaRose suggested the U.S. is still expected to become a net exporter of energy by 2020, and domestic growth in natural gas consumption will be mostly led by the industrial sector, which uses it for feedstock.

Extreme Conditions

Among the most extreme conditions for which valves must be engineered is for cryogenic applications. Brandon Bounds of Bechtel Oil and Gas said that the first specifications for cryogenics service were instituted in 1984. Standards are being continually adapted, but LNG facilities have grown in size, resulting in higher pressures and larger sized valves, leading to issues including improper welds and storage, dimensional variations and operating torque that is too high.

BoundsTest requirements for cryogenic valves are changing, according to Brian Bounds of Bechtel.He noted changes in production testing standards for cryogenic valves. These previously were specified by the purchase, but now a minimum sample size is required and there must be shell and seat testing at room temperature, as well as a system proving test at room temperature, cool down with purge gas and various other qualifications.

Continuing the LNG presentation, Jim Tesch, also of Bechtel, recommended ways to prevent serious issues; he advised against using water for testing and staying away from modifying standard valves for cryogenic service. Tesch also suggested attendees closely review non-metallic seats and seals closely and be aware of the changes upstream of the feed, which can impact many things in the process.

Changes to the fossil power generation fleet is another source of challenges for valve engineering. John Shingledecker, senior program manager of cross-sector technologies at the Electric Power Research Institute (EPRI), noted that the changing fossil fleet—a result of more renewables coming online—is creating unique challenges for valve engineers. The reduction in overall output means less money per megawatt, which leads to increased need for maintenance optimization, cost reduction and sensor technologies. More low-load operation results in a reduction in efficiencies, resulting in component operation and damage challenges.

Testing by EPRI has shown that high-temperature erosion resistance can be improved by coatings, and there are alternative materials that show improved oxidation resistance, which should lead to improved operational performances. “Alternatives to Stellite 6 will need to be considered for wear behavior for tomorrow’s power plants,” he said. Shingledecker also predicted the power generation industry and the entire integrated energy network will go through a major transformation over the next 30 years, necessitating new materials. He suggested that powder metallurgy processing, which is now code approved, opens new avenues for materials for the components.

Designing Seals and Coatings

Ryan McCall, product manager for high-performance metal seals at Technetics Group, suggested that metal seals offer the widest range of design solutions for high-temperature service and stressed that sealing must be considered early in valve design, as seal design is specific to each application. He also pointed out that the properties of a good seal were elasticity and plasticity.

MotykaElaine Motyka of Technetics compared flame spray with HVOF, pointing out the pros and cons of each method.

Elaine Motyka, principal materials engineer at Technetics, was an enthusiastic proponent of experimenting with different methods and components of thermal spray to append coatings to various materials. She compared flame spray with HVOF, pointing out the pros and cons of each method. The bottom line is that each method has its pros and cons; the best process depends on the circumstances including the process, the substrate and the coating materials. There are unlimited combinations of materials combined with processes that can result in the best coating for a particular application. It is a matter of time and budget, she said, to reach the optimal result for that application.

SuperCritical Power Generation

Charles Henley of Black & Veatch explained the difference between sub-critical and supercritical plants, and pointed out the four major systems that are unique to these power plants: the boiler feedwater, main steam, hot reheat and start-up systems. Henley also described the kind of damage that ensues when materials not designed for the high temperatures and pressures of supercritical systems are exposed to these conditions.

For the valve industry, the trend toward supercritical power generation plants means that higher fatigue cycle resistance will be required for fast responding assets. Nickel-based materials will be used for supercritical applications greater than 1200°F, but this likely will be limited to markets outside the U.S and Europe. FAC (flow-accelerated corrosion) will be a greater concern for an aging fleet built with standard carbon steels. Much more on this topic will be included in the Spring 2017 edition of VALVE Magazine.

Lean Product Development

Cliff Welborn, associate professor at Middle Tennessee State University, encouraged attendees to use the pillars of LEAN to not only manufacture products, but also to develop products. “If it takes you a long time to launch a new product, and you have high development costs, you need the life cycle of that product to be longer,” said Welborn. “If you have a lean product development cycle, you can do it, but if you have a long product development cycle, then those changing customer requirements don’t play well for you.”

To effectively institute lean product development, it’s imperative to reduce waste, and Welborn enumerated the Seven Wastes of Lean: transportation, inventory, motion, waiting, over-processing, overproduction and defects.

The Industrial Internet of Things

Mike Devrell of Rotork opened his presentation reminding the assemblage that the Internet of Things is not about things! It is about data, he pointed out: While many devices including flow control devices and smart phones and tablets are already “connected,” the data being generated by them is not necessarily being utilized.

This is in part because it’s difficult to collect data in some places, especially if it is being generated in legacy fieldbus and control systems, or in hazardous or confined spaces, but also because the different types of equipment collecting this data don’t speak to each other. Also, it is time consuming and with little perceived business benefit for many in industry.

However, he noted, if this data is properly collected and analyzed, and fused together properly, it can make field operations more efficient and safer; it can also reduce costs because maintenance can be scheduled based on reliable data on conditions rather than just a pre-set schedule. Management company McKinsey says the effective use of the Internet of Things could reduce capital expenditures by up to 20%, and financial services company Nomura says this could make oil and gas companies more profitable at $70 per barrel than they were previously at $100 per barrel.

While Devrell agreed that security is a big concern when connecting devices and sharing data through the internet, he pointed out that many of the possible dangers can be mitigated simply by properly enabling the security built into devices, using strong passwords and utilizing data diodes to securely export process data.

Valves in Oxygen Service

While oxygen itself is not flammable, it is a high-energy gas that very readily oxidizes other materials. For something to burn, the reaction requires fuel and an ignition source. Without those, no combustion will take place no matter how high the concentration of oxygen.

Kurt Larson of Air Products and Chemical pointed out the challenge for manufacturers building valves for oxygen service is to ensure they are built with the proper materials, especially seats and seals. Where the use of non-metals is unavoidable for seals, packing, gaskets, lubricants and some other components, the risks of using non-metals can be mitigated by surrounding the non-metal with metals to serve as a heat sink. It’s also essential to keep any soft goods from direct exposure to the flow stream and to prevent excessive movement.

Requirements for cleaning valves in oxygen service have been covered in VALVE Magazine in the past: Oxygen Cleaning: A Validated Process is Critical for Safety by Metso’s David Escobar, chairman of the VMA Technical Committee, is an excellent reference on this most important topic.

Standards and Specifications

Alberto Daglio of Cameron reminded attendees that, as temperatures and pressures become more severe and environmental conditions more extreme, there is increasing pressure to minimize probability of failure on demand (PFD) and maximize Mean Time Between Failures (MTBF). But there are many, sometimes conflicting, requirements depending on whether the expectations are coming from end users (specifications), governments (regulations) or standards organizations (codes).

The common goals of these requirements are to confirm the ability to seal against leakage, validate valve operating torque and thrust, determine fugitive emission performance, prove environmental containment, and prove robustness and stability of metallic trims.

Finally, Carlos Davila of Crane gave an update on ASME, API and MSS Industry Standards. A full report on these updates will be forthcoming in a future issue of VALVE Magazine. Be sure to check back frequently, as new API standards will be enumerated and new ASME B 16.25 buttwelding standards will be published later in 2017.

 

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